HR: 15:30h
AN: A53C-07    [Abstracts]
TI: Atmospheric Effects Mitigation in GNSS Relative Positioning using Wavelet Multiresolution Analysis
AU: Souza, E M
EM: eniuce@yahoo.com.br
AF: Sao Paulo State University - UNESP, Department of Cartography, Roberto Simonsen, 305, Presidente Prudente, SP 19060-900, Brazil
AU: * Monico, J F
EM: galera@fct.unesp.br
AF: Sao Paulo State University - UNESP, Department of Cartography, Roberto Simonsen, 305, Presidente Prudente, SP 19060-900, Brazil
AB: In GNSS relative processing involving long baselines, the atmospheric effect, mainly, that due to the ionosphere is one of the major errors. Although linear combination (called ion-free) of observations at the two GPS frequencies or ionosphere models can be used to mitigate ionospheric effects, they do not remove all the errors. Furthermore, depending of the region and of the ionospheric behavior, these remaining errors are very significant. This happens because the ionosphere has several irregularities and variations, such as, for instance diurnal, seasonal and solar cycle variations, as well as traveling ionospheric disturbances (TIDs), scintillation, and other geomagnetic disturbances. The short and medium-scale ionosphere irregularities (TIDs and scintillation, for example) are difficult to be taking into account or modeled. Thus, in atmospheric applications, especially for ionospheric studies, wavelet multiresolution analysis (MRA) is a powerful method to be used because it allows a time-frequency decomposition to analyze the signal in several resolutions in order to detect different scale phenomena and disturbances. In this sense, it will be present the wavelet method based on applying the MRA to the double-difference (DD) observables to detect and remove short and medium-scale ionosphere variations and disturbances, as well as short-term troposphere variations. Experiments were carried out in Brazil involving data of different baseline lengths. It was showed that even using only single-frequency data, but with MRA, one can obtain very good results, even better than those using ion-free linear combination.
DE: 1240 Satellite geodesy: results (6929, 7215, 7230, 7240)
DE: 2439 Ionospheric irregularities
SC: Atmospheric Sciences [A]
MN: 2007 Joint Assembly